[英]retrieve data of specific value in Firebase recycle view in android studio
[英]Firebase UI 3.0.0: Retrieve data to recycle view
谁能帮助我从“食物”节点中检索数据并将其放入RecyclerView
。 这些是我一直在处理的文件,但事实证明它是一个空列表。 我已经查看了Internet上的教程,但是其中大多数都是使用较旧版本的Firebase的。 最近,Firebase UI已更新,并且数据绑定过程已更改为其新的FirebaseRecyclerAdapter
结构
这是我的数据库结构:
"foods" : {
"AntipastoSalad" : {
"duration" : "30",
"img" : "https://firebasestorage.googleapis.com/v0/b/mealplanner-ec8ca.appspot.com/o/res%2Fsalad.jpg?alt=media&token=257d4392-8a1f-4fb7-84b5-b63abb4643f4",
"name" : "Antipasto salad",
"type" : "Salad"
},
这是我的活动:
private RecyclerView mRecycleView;
private Query query;
private FirebaseRecyclerOptions<Meal> options;
private DatabaseReference mDatabase;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_food_list_row);
mDatabase = FirebaseDatabase.getInstance().getReference().child("foods");
//Recycle View
mRecycleView = (RecyclerView) findViewById(R.id.meal_items);
mRecycleView.setHasFixedSize(true);
mRecycleView.setLayoutManager(new LinearLayoutManager(this));
}
@Override
protected void onStart() {
super.onStart();
query = FirebaseDatabase.getInstance().getReferenceFromUrl("https://mealplanner-ec8ca.firebaseio.com/foods/AntipastoSalad");
options = new FirebaseRecyclerOptions.Builder<Meal>()
.setQuery(query, Meal.class)
.build();
FirebaseRecyclerAdapter<Meal, FoodListRowActivity.MealRowHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<Meal, FoodListRowActivity.MealRowHolder>(
options) {
@Override
public FoodListRowActivity.MealRowHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.food_row, parent, false);
return new FoodListRowActivity.MealRowHolder(v);
}
@Override
protected void onBindViewHolder(FoodListRowActivity.MealRowHolder holder, int position, Meal current) {
holder.setTitle(current.getName());
String duration = current.getDuration() + "min";
holder.setDuration(duration);
}
};
//Populate Item into Adapter
mRecycleView.setAdapter(firebaseRecyclerAdapter);
mRecycleView.addOnItemTouchListener(new RecycleViewItemClickListener(this, mRecycleView, new RecycleViewItemClickListener.OnItemClickListener() {
@Override
public void onItemClick(View view, int position) {
Intent viewMeal = new Intent(FoodListRowActivity.this, CookingInstructionActivity.class);
startActivity(viewMeal);
}
@Override
public void onLongItemClick(View view, int position) {
//TODO: DELETE
}
}));
}
public static class MealRowHolder extends RecyclerView.ViewHolder {
View mView;
public MealRowHolder(View itemView) {
super(itemView);
mView = itemView;
}
public void setTitle(String title) {
TextView foodTitle = (TextView) mView.findViewById(R.id.list_item_foodList_name);
foodTitle.setText(title);
}
public void setDuration(String title) {
TextView foodDuration = (TextView) mView.findViewById(R.id.list_item_foodList_calories);
foodDuration.setText(title);
}
}
}
和类结构:
public class Meal{
private String img;
private String duration;
private String name;
private String instruction;
public Meal(){
}
public Meal (String img, String duration, String name, String instruction){
this.img = img;
this.name = name;
this.duration = duration;
this.instruction = instruction;
}
public void update(String duration, String name, String instruction)
{
this.name = name;
this.duration = duration;
this.instruction = instruction;
}
public String getName(){
return name;
}
public String getDuration() {
return duration;
}
public String getInstruction() {
return instruction;
}
public String getImg(){return img;}
setQuery()
方法中指定的query
应该是要在RecyclerView
显示的列表根目录的引用,如下所示:
query = FirebaseDatabase.getInstance().getReference().child("foods");
您还需要在适配器上调用startListening()
来指示适配器开始从数据库中检索数据。
从FirebaseRecyclerAdapter生命周期文档中 :
FirebaseRecyclerAdapter
使用事件侦听器监视对Firebase查询的更改。 要开始侦听数据,请调用startListening()
方法。 您可能要在onStart()
方法中调用它。 在调用startListening()
之前,请确保已完成读取数据所需的所有身份验证,否则查询将失败。@Override protected void onStart() { super.onStart(); adapter.startListening(); }
同样,
stopListening()
调用将删除事件侦听器和适配器中的所有数据。 当包含的Activity
或Fragment
停止时调用此方法:@Override protected void onStop() { super.onStop(); adapter.stopListening(); }
这是我使用Firebase UI在recyclerview中检索数据的方式:
private FirebaseRecyclerAdapter<TaskPOJO, TaskViewHolder> adapter;
private void loadTasks() {
database = FirebaseDatabase.getInstance();
tasks = database.getReference("Tasks");
adapter = new FirebaseRecyclerAdapter<TaskPOJO, TaskViewHolder>(TaskPOJO.class, R.layout.task_item, TaskViewHolder.class, tasks) {
@Override
protected void populateViewHolder(TaskViewHolder viewHolder, final TaskPOJO model, int position) {
Log.wtf("valueTEst", "populateViewHolder: "+model.toString() );
Log.wtf("TEstScript1", "populateViewHolder: "+model.getTitle() );
viewHolder.title.setText(model.getTitle());
viewHolder.desc.setText(model.getDescripttion()+"\n");
viewHolder.remaining.setText(model.getRemaining()+"/"+model.getPoint());
viewHolder.points.setText("Points "+model.getRemaining());
Glide.with(viewHolder.title.getContext())
.load(model.getImage())
.into(viewHolder.image);
viewHolder.setClickListener(new ItemClickListener() {
@Override
public void onClick(View view, int position, boolean isLongClick) {
Toast.makeText(getActivity(), "" /*+ model.getTitle()*/, Toast.LENGTH_SHORT).show();
Intent TaskPOJODetail = new Intent(getActivity(), Main.class);
TaskPOJODetail.putExtra("value","detail");
TaskPOJODetail.putExtra("taskId",adapter.getRef(position).getKey());
startActivity(TaskPOJODetail);
}
});
}
};
progressBar.setVisibility(View.GONE);
recyclerViewTasks.setAdapter(adapter);
}
这是我的firebase结构:
希望这会帮助你。
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